As far as i'm aware E90 kept the excellent drum inside disc design of parking brake as fitted to E46 (an expensive to make quality system, not like the cheap to manufacture self adjusting calipers some other makes fit), so the foot brake calipers are like any normal front disc brake in that the pistons will push back in, no special tools required.

Look online for how to slacken off the parking brake shoes, if they have worn a groove in the existing drums then without adjusting them off you'll find it difficult to remove the disc/drums...note you might have to jack the car up again after a few miles to re-adjust the parking brake shoes once they have bedded in.

I suggest you try and do the job when a good motor factor is open, just in case you need new parking brake shoes too..unlikely but you never know and its very annoying when you have this type of brake all apart then find a parking brake shoe is past its best and no one likely to stock them open...ask me how i know this :-) unless you're brake supplier will let you return parking brake shoes if not needed if you buy them before doing the job.

Edited by gordonbennet on 03/11/2018 at 15:17